The timing of planting shallots (Allium ascalonicum L). Based on Soil Water Balance Land in districts Petang, order to determine the water balance Land in Districts Petang, knowing Water balance land and crop water needs shallots so that can determine the time of planting shallots right in District Petang. This study uses the average precipitation, humidity, solar radiation, wind speed andÂ temperature. From the average data of climate is then used to calculate potential evapotranspiration (ETo) using CropWat application for windows. ETo of calculation is used to analyze the soil water balance, using the method of Thornthwaite and Mather, (1957). The results showed that potential evapotranspiration in the evening during the year amountedÂ to 1643 mm with actual evapotranspiration (ETA) of 1591 mm. Periods of water surplus land in the evening lasted for seven months in November - in May. Water re-charging period (recharge) to the land which has been experiencing drought occurred in November, the best planting time for the shallots in Petang is December. With increasing water needs in accordance with the increasing age of the plant, which peaked in mid-stage season stage. Thus the plants can utilize the water contained in the soil for the growth of vegetative and generative growth of these plants do not require much water and harvest is expected in February.